Chemical Composition and Thermal Stability of Atomic Force Microscope-Assisted Anodic Oxides as Nanomasks for Molecular Beam Epitaxy

We have investigated the thermal stability of GaAs-oxides grown by atomic force microscope (AFM)-assisted anodic oxidation to identify the conditions suitable for fabricating oxide nanomasks for molecular beam epitaxy (MBE). The oxides grown at bias voltages, $V_{\text{ox}}$, less than 30 V were desorbed after standard thermal cleaning in MBE, while the oxide patterns fabricated at $V_{\text{ox}} \geq 40$ V survived on the GaAs surfaces. From X-ray photoemission spectroscopy, we have found that the better thermal stability of AFM-oxides grown at $V_{\text{ox}} > 40$ V can be attributed to the formation of Ga 2 O 3 and that Ga 2 O 3 can be used as nanomasks for site-controlled MBE growth.